#include <iostream>

using namespace std;

int Fact(int n)
{
	if (n < 2)
		return 1;
	else
		return n * Fact(n-1);
}

int main()
{
	int n; cin >> n;
	int ret = Fact(n);
	cout << ret << endl; 
	
	
	return 0;
}
